1. Field of the Invention
The present invention concerns a method in order to correct the phase information in the creation of magnetic resonance (MR) images that have been acquired with an echoplanar method. Moreover, the present invention concerns a correspondingly designed magnetic resonance system.
2. Description of the Prior Art
Functional MR imaging (fMRI), in which the oxygen saturation of blood is depicted, for example, is a popular method in order to non-invasively study the active brain, for example. The oxygen saturation of the blood changes depending on local activation in the brain, and the T2* relaxation time changes, and so the acquired MR data change, based on this changing oxygen saturation. The complex-value fMRI signals thus contain physiological information.
The underlying requirement for an analysis by means of fMRI is the stability of the measured MR signals, both spatially and temporally. These requirements also apply for other applications, for example in the generation of MR images with which a diffusion or perfusion map is presented. The spatial stability (i.e. the assumption that a predetermined magnetic field strength respectively prevails at a defined location of the examination subject) can be disrupted, for example, by breathing or the heartbeat or by a movement of the examination subject. The temporal stability (i.e. the assumption that a predetermined magnetic field strength prevails at a defined location at a defined point in time or during a predetermined time interval) can be disrupted, for example, by a corresponding drift of the magnetic resonance system.